الفهرس 
Introduction
Effect of PHOnly 14 pages are availabe for public view
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Abstract
Urease from the cotyledons of Cucurbita pepo expressed maximum activity at the 5th day of germination.
Urease was activated when treated with growth regulators such as, IBA, NAA, IAA, IPA and zeatin, 6-BA, kinetin, HBL and triazoles.
Urease was inhibited by AlCl3 and CdCl2. CdCl2 was stronger inhibitor than AlCl3.
Urease was purified by using ammonium sulfate (40- 80 %), phenyl Sepharose, Sephadex G-200 and hydroxylapatite. The specific activity was 580 U mg-1protein.
Urease was stabilized by dicarboxylic anhydrides: citraconic anhydrides (CA), malic anhydrides (MA), phthalic anhydride (PA) and succinic anhydride (SA) at 60 ºC and 70 ºC.
The results revealed that lysyl, tyrosyl and tryptophanyl residues are taking part in enzyme catalysis.
Urease was successfully immobilized on chitosan, chitin and alginate, but immobilization on chitosan was most effective.
The optimum temperatures for free and immobilized urease were 40 ºC and 45 º, respectively.
The immobilized urease exhibited better resistance against inhibition by CdCl2 and AlCl3 when treated with tested organic solvents namely: methanol, ethanol and propanol than the free enzyme.